Enameled ware



Patented June 3, 1924.

umrao STATES PATENT OFFICE.

HAROLD I. WHITTAKER, OF CARNEYS' POINT, NEW JERSEY, AND THEODORE BAKER,

OF WILMINGTON, DELAWARE, ASSIGNORS T0 E. I. DU PONT- DE NEMOURS & COH- PANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

ENAMELED No Drawing.

To all whom it may concern:

Be it known that we, HAROLD F. WHIT- TAKER and THEODORE BAKER, citizens of the United States, and residents of Carneys Point, in the county of Salem and State of New Jersey, and Wilmington, in the county of New Castle and State of Delaware, respectively, have invented a certain new and useful Enameled Ware, of which the tollowing is a, specification.

This invention relates to improvements in enameled ware in which an enamel of a glassy nature is fused onto a metallic base to produce apparatus of greater resistance 'to wear and corrosion than has the bare metal base.

In this industry the most commonly used metal bases are cast iron and steel; other metals are mostly less suitable either because of their prohibitive price, too great coefiicient of expansion, or low melting point. The enamels for this work have to be most carefully chosen and compounded so that differences in expansion and contraction and their ill efi'ects will be minimized, and this has-been done to the detriment of the resistance of the enamel to corrosion, as will be explained in greater detail later on.

The object of our invention is to so compound the metal base by employing a suitable alloy that the expansion coeflicient of thebase is adjusted to suit that of the enamel, allowing the composition of this to be chosen as most suitable from every other point of view, especially thatof chemical resistance.

.As examples of the materials hitherto.

added to enamels to render their expansion and contraction similar to that of the iron or steel base there may be mentioned the oxides of iron, lead, cobalt and nickel, as well as certain compounds of boron and fluorine. These ingredients also materially lower the -fusing point of the enamel and facilitate the burning on in a uniform layer. On the other hand, borax imparts to the enamel certain undesirable properties, among them being a solvent action on the opacifying agents and most im ortant of all, it im parts to the enamel a ecided susceptibility to corrosive action. The same is .true, to some extent, of fluorides. Although fluor- 1 spar acts as an opacifier when added in large amounts, it is known to have, when present Serial No. 485,304.

to the extent of morethan3%, a decidedly weakening effect upon the resistance of the enamel to the solvent action of acids, alkalies or water. The adjustment of the coefficient of expansion of the metal base will make possible the use of a more acid resistant enamel, since the differential coefiicient of expansion between the selected enamel and the metal base can be reduced to a very low figure and thus prevent the usual checking and chipping of the enamel coating when subjected to temperature changes while in operation. A

Our method of controlling the expansion coeflicient of the iron or steel is to add, as an ingredient thereto, a suitable amount of nickel with minor optional additions of such other materials as manganese, chromium, tungsten, Vanadium, or cobalt.

The above method of adjusting or controlling the coefiicient of expansion of the metal base so that it will conform with that of the selected enamel. is illustrated by the following example. The iron or steel alloy,

which is used as the base metal for the enamel coating, should have a composition within the following limits.

Per cent. Iron or steel. to 68 Nickel 32 to 43 Chromium O to 10 Carbon 0 to 0.2 Manganese 0 to 1.0 Phosphorus -notover .05 Sulphur not over .07

I. II. III.

Per cent. Per cent. Per cent. Iron 57. 48 56. 23 68. 93 Nickel 42.00' 36.2) 30.00 Chromium (I) 7. M 1. Carbon. i0 l0 10 Manganese. 35 0 ll Phosphorus (B .03 .oa Sulphur .Ol 04 04 The presence of carbon in the iron or steel, even in amounts as small as .10 or has a tendency, especially with certain proportions of iron and nickel, to cause wide fluctuations in the coelficient of expansion at different temperatures; this tendency is counteracted to a certain extent if chromium is present. The use of chromium is also desirable for the reason that it facilitates an adjustment of the coefficient of expansion within certain limits. Thus for a nickel-iron alloy containing about 36% Ni the coefiicient of expansion varies, between 2 x 10" and 7.5 x 10, almost directly as the percentage of chromium between 1 and 10%.

The composition of the enamel according to our invention may approximate the composition of glasses in common use for laboratory'ware, e. g. 2-

Percent s10. 67 B 0, 6.9 Na,() 8.5 K 0 0.4 a0 7.0 MgO 0.2 A1203 100 The above enamel formula is, of course,

, merely illustrative; any enamel composition having high chemical resistance or other desirable properties incompatible with a high coeflicient of expansion may be said to comewithin the purview of our invention.

For example, many compositions of enamels having the desired chemical andphysical properties have components whose pro ortions come within the limits set forth in t efollowing table Per cent.

SiO 67.0 to 75.0 B 0 4.0 to 24.0 Na O 4.0 to 8.5 K 0 0.2 to 1 3 CaO 0.2 to 7 0 MgO 0.0 to 0 5 A1 0 0.0 to 10 0 Pb 0.0 to 1.0

terial into the desired form, and applying thereto the enamel.

2. In the method of making chemically v expansion, and a metallic base consisting of an alloy whose coeflicient of expansion is substantially the same as that of the enamel.

4. As a new article of manufacture, an enameled iron alloy comprising an enamel having high chemical resistance and a relatively low coefiicient of expansion, and a base consisting essentially of iron and a sufficient amount of another metal to form an alloy whose coeflicient of expansion is substantially the same as that of the enamel.

5. As a new article of manufacture, an enameled iron alloy comprising an enamel having high chemical resistance and a relatively low coefficient of expansion, and a base consisting essentially of iron and a sufficient amount of nickel to form an alloy whose coeflicient of expansion is substantially the same as that of the enamel.

6. As a new article of manufacture, an enameled iron alloy comprising an enamel having a relatively low coeflicient of expansion, and an alloy having substantially the same coeflicient of expansion and containing between 50 and 68% of iron and between 43 and 32% of nickel. I

7. As a new article of manufacture, an enameled iron alloy comprising an enamel having a relatively low coeflicient of expansion and high chemical resistance, and an alloy having substantially the same coefficient of'expansion and consisting essentially of iron, nickel, and chromium.

8. As a new article of manufacture, an enameled iron alloy comprising an enamel having a relatively low coeflicient of expansion and high chemical resistance, and an alloy having substantially the same coefficient of expansion and containing between 50 and 68% of iron, between 43 and 32% of nickel, and between 0.0 and 10% of chromium.

9. As a new article of manufacture, an enameled iron alloy comprising an enamel having a relatively low coeflicient of e ansion and high chemical resistance, an an alloy having substantially the same coeflicient of expansion and containing from about 58 to 60 parts of iron, about 39 parts of nickel, from about 1 to 2 parts of chromiun, about 0.1 part of carbon, and about 0.4 parts of manganese.

10. Asa new article of manufacture, an enameled iron alloy comprising an enamel whose components are present in the following proportions:

' Per cent. SiO, 67.0to75.0 B 4.0 to 24.0 H21 6 4 0 to 8 5 0 0.2 to 1 3 C210 0.2150 0.0to 05 ,0 0.0 to 10 0 PhD 0.0 to 1 O and an alloy having substantially the same coeflicient of expansion as said enamel.

11. As a new article of manufacture, an enameled iron alloy comprising an enamel lowing proportions:

- Percent.

sio, 67.0to75.0

I B,0 4.0to24.0 N '6 4.0m 8.5 K2) 0.21 1.3 CaO 0.2to 7.0 Pal-0 0.0to 0.5 0, 0.0m10.0 PbO 0.0 to 1.0

and an alloy having substantially the same between 43 and 32% of nickel.

' coeflicient of expansion as said enamel and containing between 50 and 68% of iron and 35 In testimony whereof we afiix our signatures.

HAROLD F. WHITTAKER.

' THEODORE BAKER. 

